During the mechanical ventilation of patients on an intensive-care ward, for example, the patient to be ventilated is connected pneumatically to the ventilation device by means of a breathing tube system. Because the breathing gas which is delivered to the patient must be adjusted with respect to temperature and humidity to the physiological needs of the patient, a respiratory humidifier is arranged in the inhalation or inspiration tube to heat and humidify the breathing gas. The respiratory humidifier comprises a liquid container filled with distilled water in the usual manner; the inhalation gas is conducted through this container, and its moisture content is thus increased.
To prevent moisture from condensing inside the breathing tube system, the inhalation tube and the expiration or exhalation tube are usually provided with electrical tube heaters, which heat the inhalation and exhalation gas flowing through them during operation. A loop of heating wire, for example, is used, which is integrated into the interior of the inhalation or exhalation tube, or the inhalation or exhalation tube is wrapped in each case with a coil of heating wire.
The breathing gas temperature is usually regulated by means of a temperature sensor arranged near the patient; this sensor is connected by an electrical measurement line to a control unit, which is arranged in, for example, the respiratory humidifier or in the ventilation device.
When newborns or infants are being ventilated in the neonatology department, there is the special circumstance that these patients are lying in incubators or humidicribs or warming beds, the temperature of which is usually kept at about 37° C. and thus above the temperature of the climate-controlled environment. For this reason, the area of the inhalation tube located inside the incubator or warming bed, for example, must be supplied with less heat or no heat at all, in contrast to the area of the tube located outside, which must continue to be heated to prevent condensation.
Previous approaches to the solution of this problem consisted, for example, in constructing the inhalation tube in such a way that the temperature sensor is attached at either one of two different positions on the tube depending on the application, that is, on whether an incubator is involved or a warming bed with radiation from an (infrared) heating lamp, and in using an additional, unheated piece of extension tubing at the end of the inhalation tube, upstream of the Y-piece.
Another approach is disclosed in DE 10 2007 003 455 A1, in which adapters are inserted into the inhalation and exhalation tubes; these adapters divide each of the overall heating sections into two heating subsections, one inside, the other outside the incubator. The two sections are heated independently of each other.
DE 20 2006 007 397 U1 describes a ventilation tube with different heating zones to deal with the different climate zones associated with infant incubators.
Solutions of this type are complicated to operate; they are also complex and thus lead to considerable cost. Because, for hygienic reasons, the system of tubing in ventilation systems frequently consists of medical-grade, single-use or disposable articles, approaches of this type do not lead to the goal envisioned here.